Not A Number in IEEE Math

[mac at ardent.com]

  In article <44 at newave.UUCP> john at newave.UUCP (John A. Weeks III) writes:

>  Xref: ardent comp.lang.c:24861 comp.sys.ibm.pc.programmer:25
           ^ why ardent?
>  My understanding of the NaN (not a number) value in IEEE math is
>  that once you get NaN, the operators +, -, /, *, and = are supposed
>  to propagate the NaN value.  Is my understanding correct?
>  
>  Well, while using MetaWare's HIGH-C compiler for the 80386 chip, I
>  have discovered that:
>  
>  			NaN / NaN = 1.0
>  
>  			      and
>  
>  			0.0 * NaN = 0.0.
>  
>  Is this correct behavior?  I think HIGH-C is broken...
>  
>  -john-

	This behaviour is not correct.  Possibly the compiler has
folied you by presubstituting 1.0 for A/A and 0.0 for 0.0 * A at
compile time.
	
	Or, perhaps your hardware traps into the OS for IEEE exceptions
and the OS's handling of source exceptions is broken.

	Or, perhaps your hardware is not IEEE compliant....



--
Michael McNamara	(St)ardent, Inc.		mac at ardent.com